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    SubjectRe: soft update vs journaling?
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    Diego Calleja wrote:
    > El Sun, 22 Jan 2006 04:31:44 -0500,
    > Theodore Ts'o <tytso@mit.edu> escribió:
    >
    >
    >
    >>One major downside with Soft Updates that you haven't mentioned in
    >>your note, is that the amount of complexity it adds to the filesystem
    >>is tremendous; the filesystem has to keep track of a very complex
    >>state machinery, with knowledge of about the ordering constraints of
    >>each change to the filesystem and how to "back out" parts of the
    >>change when that becomes necessary.
    >
    >
    >
    > And FreeBSD is implementing journaling for UFS and getting rid of
    > softupdates [1]. While this not proves that softupdates is "a bad idea",
    > i think this proves why the added sofupdates complexity doesn't seem
    > to pay off in the real world.
    >

    Yeah, the huge TB fsck thing became a problem. I wonder still if it'd
    be useful for small vfat file systems (floppies, usb drives); nobody has
    led me to believe it's definitely feasible to not corrupt meta-data in
    this way.

    I guess journaling is looking a lot better. :)

    > [1]: http://lists.freebsd.org/pipermail/freebsd-hackers/2004-December/009261.html
    >
    > "4. Journaled filesystem. While we can debate the merits of speed and
    > data integrety of journalling vs. softupdates, the simple fact remains
    > that softupdates still requires a fsck run on recovery, and the
    > multi-terabyte filesystems that are possible these days make fsck a very
    > long and unpleasant experience, even with bg-fsck. There was work at
    > some point at RPI to add journaling to UFS, but there hasn't been much
    > status on that in a long time. There have also been proposals and
    > works-in-progress to port JFS, ReiserFS, and XFS. Some of these efforts
    > are still alive, but they need to be seen through to completion"
    >

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